AlistGo/alist · error

that's not even a token

Error message

that's not even a token

What it means

ParseToken maps jwt.ValidationErrorMalformed to this message: the string is not a well-formed JWT at all — it could not be parsed into three dot-separated base64 segments with valid structure.

Source

Thrown at server/common/auth.go:51

	tokenString, err = token.SignedString(SecretKey)
	if err != nil {
		return "", err
	}
	validTokenCache.Set(tokenString, true)
	return tokenString, err
}

func ParseToken(tokenString string) (*UserClaims, error) {
	token, err := jwt.ParseWithClaims(tokenString, &UserClaims{}, func(token *jwt.Token) (interface{}, error) {
		return SecretKey, nil
	})
	if IsTokenInvalidated(tokenString) {
		return nil, errors.New("token is invalidated")
	}
	if err != nil {
		if ve, ok := err.(*jwt.ValidationError); ok {
			if ve.Errors&jwt.ValidationErrorMalformed != 0 {
				return nil, errors.New("that's not even a token")
			} else if ve.Errors&jwt.ValidationErrorExpired != 0 {
				return nil, errors.New("token is expired")
			} else if ve.Errors&jwt.ValidationErrorNotValidYet != 0 {
				return nil, errors.New("token not active yet")
			} else {
				return nil, errors.New("couldn't handle this token")
			}
		}
	}
	if claims, ok := token.Claims.(*UserClaims); ok && token.Valid {
		return claims, nil
	}
	return nil, errors.New("couldn't handle this token")
}

func InvalidateToken(tokenString string) error {
	if tokenString == "" {
		return nil // don't invalidate empty guest token

View on GitHub (pinned to 843d9dc814)

Solutions

1. Ensure the client sends a JWT issued by /api/auth/login in the Authorization header
2. Split the header correctly (strip the "Bearer " prefix, handle case) before calling ParseToken
3. Validate shape first: token must have 3 dot-separated, non-empty segments

Example fix

// before
tokenString := strings.TrimPrefix(authHeader, "bearer ") // wrong case handling left 'Bearer '

// after
parts := strings.SplitN(authHeader, " ", 2)
if len(parts) != 2 || !strings.EqualFold(parts[0], "Bearer") {
    return errors.New("malformed authorization header")
}
tokenString := parts[1]

func looksLikeJWT(s string) bool {
	p := strings.Split(s, ".")
	return len(p) == 3 && p[0] != "" && p[1] != "" && p[2] != ""
}

func isJWT(s string) bool { return looksLikeJWT(s) }

_, err := common.ParseToken(tok)
if err != nil && strings.Contains(err.Error(), "not even a token") {
	// reject the credential outright; do not retry
}

When it happens

Trigger: Passing "abc", a base64 blob without dots, a truncated token, or a non-JWT string (e.g. a raw API key or sign string) to ParseToken.

Common situations: Authorization header parsing bug that passes "Bearer" without the token; client sends the wrong credential type; token mangled by a proxy or copy/paste truncation.

Related errors

• token is invalidated
• token is expired
• token not active yet
• couldn't handle this token
• failed to refresh token: sub not match

AI-assisted analysis of AlistGo/alist@843d9dc814 (2026-08-15). Data as JSON: /api/errors/64cbe51f0165af62. Report an issue: GitHub.